{"id":31173,"date":"2014-03-27T00:09:41","date_gmt":"2014-03-27T07:09:41","guid":{"rendered":"http:\/\/www.todayifoundout.com\/?p=31173"},"modified":"2014-03-27T03:27:04","modified_gmt":"2014-03-27T10:27:04","slug":"sun-burns-skin-sunscreen-prevents","status":"publish","type":"post","link":"http:\/\/www.todayifoundout.com\/index.php\/2014\/03\/sun-burns-skin-sunscreen-prevents\/","title":{"rendered":"How the Sun Burns Your Skin and How Sunscreen Prevents This"},"content":{"rendered":"
Our resident medical expert, Scott, and a buddy of his recently started The Medicine Journal<\/a>, where you can learn all sorts of interesting facts about all things medical related. Below is a sample article from their site.<\/div>\n

\"sunscreen\"<\/a>Every summer we slather layers of sunscreen with the highest SPF we can find, and bravely venture outside hoping our slimy cloak will shield us from the sun’s death rays. \u00a0So how does this work?<\/p>\n

To start off, what is a sunburn? \u00a0In the medical world, a sunburn is known as erythema.\u00a0 Basically meaning the redness of skin caused by dilatation and congestion of the capillaries, and is often a sign of inflammation or infection.\u00a0 \u00a0Several things can cause your skins capillaries to become inflamed.\u00a0 Things like infection, allergies, mercury toxicity, tweezing or pulling on your hair follicles, and of course, the sun\u2019s ultraviolet rays.<\/p>\n

The ultraviolet (UV) rays that cause sunburns come in two forms. \u00a0UV-A and UV-B.\u00a0\u00a0 These rays, like all electromagnetic radiation, come in waves at specific frequencies.\u00a0 UV-A has wavelengths between 315-400 nanometers. \u00a0UV-B wavelengths are between 280-315 nanometers.\u00a0 These wavelengths penetrate the skin and get absorbed at various depths.\u00a0\u00a0 The damaging effects of sunlight generally reside in wavelengths between 290-400 nanometers.<\/p>\n

Our atmosphere actually does a pretty good job of filtering out most of the harmful UV radiation.\u00a0 95% of the UV energy hitting the earth\u2019s surface is UV-A.\u00a0 The other 5% is UV-B. \u00a0\u00a0In fact, almost all of UV-B radiation is absorbed by our atmosphere. \u00a0UV-A penetrates the skin more deeply than UV-B. That said, while UV-A does plenty of damage on its own, ray for ray, it’s UV-B that causes more problems generally associated with exposure to the sun’s rays, like skin cancer, aging, and DNA damage. \u00a0It\u2019s also UV-B waves that are primarily responsible for your sunburned skin.<\/p>\n

How do these rays cause erythema and the pain that comes with it?\u00a0 UV-B wavelengths don\u2019t penetrate very deeply, but they cause photochemical reactions in your epidermis (the outer layer of your skin) and damages DNA.\u00a0 The body\u2019s natural response is to trigger several reactions by your immune system.\u00a0 The result is increased blood-flow to your capillary beds (vasodilation) and swelling (edema) which help in bringing certain cells that repair the damage.\u00a0 This also triggers the body to produce more melanin (skin pigment) to help in future exposures.\u00a0 The result of all this is the reddening of your skin.<\/p>\n

Another protein molecule, known as CXCL5, also triggers specific immune cells in response to UV-B radiation.\u00a0 It\u2019s thought that this molecule is what causes the pain and tenderness associated with your burn by stimulating the nerve endings in your skin.<\/p>\n

All of these reactions don\u2019t happen right away.\u00a0 They usually begin around 4 hours after exposure and peak between 8-24 hours.\u00a0 This is why you might feel fine right after you leave the beach, but by the time you hit the shower the next morning, your back looks like a tomato and the hot water feels like you’re being burned at the stake.<\/p>\n

Sunscreen works in two ways to protect you from this.\u00a0 It either absorbs the UV wavelengths or scatters and reflects it. \u00a0 Two organic compounds that absorb UV-B light, and dissipate it as heat, are octyl methoxycinnamate and oxybenzone.\u00a0\u00a0 Inorganic compounds that reflect and scatter UV-A radiation before the skin can absorb it includes zinc oxide and titanium oxide, among others.<\/p>\n

Depending on the specific makeup of your sunscreen, it will come with protection known as Sun Protection Factor (SPF).\u00a0 If you would normally burn in 10 minutes, a SPF of 15 would allow you protection up to 150 minutes.\u00a0 An SPF of 30 would allow you 300 minutes, and so on.<\/p>\n

Don\u2019t think, however, you are actually doubling your protection every time you double the SPF.\u00a0 As many consumer watch groups point out, an SPF of 15 filters out around 92% of UVB radiation.\u00a0 An SPF of 30 will only absorb about 96.7%, and an SPF of 40 will absorb 97.5%. \u00a0\u00a0They also point out that while sunscreens are often advertised as \u201cSun-Block\u201d, many are actually only blocking UV-B rays, and not UV-A.\u00a0 To make sure you’re getting true broad spectrum protection, your sunscreen must contain both the organic compounds associated with UV-B absorption and the inorganic associated with UV-A reflection. Many that do this will specifically say they block both of these so you needn’t necessarily remember which chemicals do what.<\/p>\n

If you\u2019re like me, you\u2019ve never been scared of a little sunburn.\u00a0 In fact, you prefer it to the slimy skin associated with sunscreen.\u00a0 But be afraid, very afraid.\u00a0 Countless studies have shown exposure to the sun\u2019s harmful rays are responsible for early aging and an increased risk of skin cancer.\u00a0 You might think this risk is minimal.\u00a0 You’re probably wrong.<\/p>\n

A review published in JAMA Dermatology in January of 2014 showed that exposure to the UV wavelengths associated with indoor tanning beds account for nearly twice as many skin cancer diagnosis as smoking does lung cancer in the United States-\u00a0 about 400,000 annually for tanning beds, compared to 200,000 from smoking.\u00a0 Further, even just one tanning bed session increases your risk of getting melanoma- the deadliest form of skin cancer- by 75%. This is why the American Medical Association, the American Academy of Pediatrics, the American Academy of Dermatology, the Skin Cancer Foundation, and the World Health Organization have all called on every state to ban children under 18 from using tanning salons.<\/p>\n

If you\u2019re also like me, you might try and justify not using sunscreen by saying; \u201cWell, tanning booths primarily use UV-A radiation and emit it much more intensely than just standing out in the sun.\u00a0 Further, the damage by natural sunlight is caused mainly by UV-B waves.\u00a0 So I simply won\u2019t visit tanning booths, and, rather, burn my skin the natural way.\u201d\u00a0 Unfortunately, upwards of 90% of the visible changes commonly attributed to skin aging are thought to be caused by the sun.\u00a0 Combined with the fact that 1 in 5 Americans will develop skin cancer in their lifetime, with the sun being public enemy number one here, even natural sunlight should be fought off with copious amounts of sloppy, broad-spectrum, high SPF goo.\u00a0 Or, you could simply convert to living the life of a blogger, safely nestled away in our stereotypical mothers’ basements. \ud83d\ude09<\/p>\n

If you liked this article, you might also enjoy our new popular podcast, The BrainFood Show (iTunes<\/a>, Spotify<\/a>, Google Play Music<\/a>, Feed<\/a>), as well as:<\/p>\n